Brief Introduction:
MZ31 series of PTC thermistor is a million- time safety device of automatic protection,recoverability, using repeatedly, and no trigger, noise or protective components that could protect and restore from abnormal temperature and current automatically,which called "auto restore fuse" and "ten-thousand-time fuse".Recoverability, using repeatedly, and no trigger, noise or sparks.
Working principle:
As indicated in Fig 2 as below,when circuit is in the normal state, the current through PTC is lower than the rated current and PTC is in the normal state with small resistance value,which will not affect the normal
operation of the protected circuit such as primary and secondary loops of the voltage transformer.In case of some trouble in the circuit and the current is bigger than the rated current,the PTC will become hot quicklyand
present high resistance value, which sets the circuit relatively “off” to protect the circuit from damage.After the trouble is removed,PTC will automatically restore its low resistance state and the circuit will resume
normal operation.
Product Applications:
overcurrent,overload and short circuit protection of general circuit,e.g. transformers,mico motor,switch power,electric energy meter,charger,adaptor,meter,apparatus,electronic coils,control panels,home appliances,air
conditioning,microwave oven etc. Overcurrent protection of intelligent watt-hour meter RS485 interface, digital multimeter,micromotor and transistor.
Advantages:
1.Automatic protection,can resume steadily ;
2.contactless,noiseless and flameless;
3.reacts fast;
4. with a better performance of withstanding voltage；
5.small steady resistance;
6.low rated current.
Choose guidelines of PTC resistor for protection of overcurrent and overload:
In selecting PTC thermistor as overload protection component,firstly,make sure of the maximum operating current in the circuit(non-trip current of PTC thermistor) and maximum operating voltage,rated zero power resistance,and also the outlook and dimension should be also taken into consideration.Relation between operating temperature,operating current and non-operating current is as shown in Fig 3 as below.Operating current is normally 2-3 times compared as non-operating current,and both of the currents
will be reduced as operating temperature increases.
Many specifications for choice,and samples&orders can be custom made per customers' requirement.
